Ihave installed Exchange 2003 on a Small Business Server and maintained it since. ButI am being offer a job that requiresan Exhange deployment on a larger scale, and I just want to make sure that I can handle it. The questions I was asked was: "What would be the major issues with an Exchange implementation from an architectural and security aspect?" Any help?

This is a very open ended question, really the best that you can do would be to read thoroughly the Exchange help file (2007) and the other MS documentation available in particular the deployment and administration guides. After that, keep an eye on the MSExchangeTeam websites and also the msexchange.org sites. Cheers Nathan